Pulseless pump

ABSTRACT

A multiple cylinder pump in which the cylinders are arranged in pairs and the plungers of each pair are moved forward alternately and are returned to their initial positions by a cam for each cylinder. Furthermore, the cylinder sealing devices are easily accessible for maintenance and can be adjusted while the pump is operating.

United States Patent 1191 1111 3,792,939

Zalis Feb. 19, 1974 PULSELESS PUMP 1,738,104 12/1929 11311 417/516 x [75] Inventor: Albert A. Zalis, Warren, Mass.

73 Assigneez w Pumps, Inc Nan-eny Mass 3,330,217 7/1967 Baur et al. 417/454 X [22] Ffled: 1972 Primary ExaminerC. J. Husar [21] Appl. No.: 241,555 Assistant Examiner-Le0nard Smith Attorney, Agent, or Firm-Norman S. Blodgett [52] US. Cl 417/539, 92/171, 277/102,

417/454, 417/568 [57] ABSTRACT [51] Int. Cl. F04b 39/10 58 Field of Search.....-. 417/454, 539, 568; 92/171; A mumpl? 'f Pump the i are 2.77/35 51 102 113 arranged 1n pans and the plungers of each pair are moved forward alternately and are returned to their [56] References Cited 1n1t1al posltlons by a cam foreach cylmder. Furthermore, the cylmder sealmg devlces are easlly accesslble UNITED STATES PATENTS for maintenance and can be adjusted while the pump 3,137,216 6/1964 Aytes 92/171 is perating 2,655,870 10/1953 Yohpe 417/568 3,556,690 1/1971 Scheffer 417/539 X 5 Claims, 6 Drawing Figures PATENTEDFEB 19 1974 sum 3 or a vwI PATENTEDFIEB 19 m4 SHEEI' Q 0F 4 FIGS PULSELESS PUMP BACKGROUND OF THE INVENTION The invention relates to cam-actuated multiple cylinder pumps of the constant output pressure variety, in which the plungers are moved forward and returned by cam action. To accomplish this, a yoke is positioned around each cam.

The advantages of utilization of piston and cylinder pumps in certain pumping and metering applications is well recognized. The standard constructions have two major disadvantages, however. First, their output pressure is seldom uniform and, second, the operating speed, and thus capacity is limited. In these constructions the reciprocating motion of the piston is caused by either a crank and piston rod or scotch yoke. Although the piston exhibits a sinusoidal motion, time lags in the action cause the input and output pressure to deviate considerably from a sine wave. This deviation gets worse, with increasing speed. The importance of the sinusoidal output pressure is that if it is combined with the like output of one other cylinder, 180 out of phase, the result is a perfectly constant output pressure.

Accomplishing this, even approximately, with old constructions is not a simple problem and becomes more difficult as operating speed increases. It was determined that a properly designed cam actuated device could cause reciprocation that would compensatefor the time lags. Muellers design included a double acting pump operating on both of the needed cylinders. It turned out that a single-acting arrangement is some what better adapted to cam actuating mechanisms when high operating speeds are intended.

It is important to recognize in role of operation speed in a positive displacement pump. Generally, a pump can be replaced by a new pump of half the size if the smaller pump can be operated at twicethe speed of the old pump. This increase in operating speed is possible with the cam pump, because the cam design can compensate for the time lags at extremely high speeds. At this point, other factors begin to limit operating speed. Although input and ouput wear is decreased by strict adherance with sinusoidal pressure waves, seal wear and dynamic balancing becomes a problem at higher speed.

These and other difficulties experienced with the prior art devices has been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide an effective design for a multiple cylinder pump having a constant output pressure and capable of high operating speed.

Another object of this invention is the provision of a multiple cylinder pump with provision for dynamic balancing.

A further object of this present invention is the provision of a multiple cylinder pump in which leaking seals can be adjusted while pump is operating and without inconvenience.

It is another object of the instant invention to provide a multiple cylinder pump in which important seals form a single cartridge which can be replaced as a unit.

A still further object of the'invention isthe provision of a multiple cylinder pump in which the main cylinder seal can be removed outboard of the cylinder.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

SUMMARY OF THE' INVENTION This invention relates to a multiple cylinder pump having a set of pistons, one of which is made to reciprocate in each cylinder by a cam actuated drive. Furthermore, the drive can be dynamically balanced and seals in high wearing situations are easy to adjust and replace. The pump is capable of high operating speed and produces constant pressure output.

BRIEF DESCRIPTION OF THE DRAWINGS The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings, in which:

FIG. 1 is a plan view of the entire machine partly in horizontal section,

FIG. 2 is a vertical transverse section, partly through the cam shaft and partly through the following bearings,

FIG. 3 is a side view in longitudinal section of one of the pumping units along line IIIIII,

FIG. 4 is a view in cross-section along line IV-IV,

FIG. 5 is a view in cross-section along line IV-IV,

FIG. 6 is a side view in longitudinal section of a pumping cylinder.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention would be applicable to a pumping apparatus containing only two pumping units, but the capacity is greater if four units are used, as shown on the drawings.

The general arrangement of the preferred construction is shown in FIG. 1 and comprises a cam shaft 1 carrying four cams arranged in pairs, each pair consisting of two cams 2 and 3 of identical dimensions but spaced angularly l from each other. The cam shaft is journalled in three roller bearings 4, 5, 6, although other kinds of bearings could be substituted. Eccentrics 11 are provided at each end of the cam shaft for dynamic balancing of the rotating system.

Referring to FIG. 3 which shows the details of each plunger unit, each cam 2 is enclosed in a yoke 13 on the head 14 of a'plunger 15 whose opposite end reciprocates in a fluid-tight cylinder plunger seal 16 and terminates in a cylinder 17 that is fluid-tight, except for the usual opening check valves 18 and 19. The yoke 13 includes a forward yoke half 5 mounted on the plunger head 14. Rotatably mounted in the forward yoke half on an axis parallel to the cam shaft is a roller bearing 6. The Yoke also includes a following yoke half 7 resiliently connected to the forward yoke half by bolts 9 and springs 10. The following yoke half also carries a rotable roller bearing 8 with its axis parallel to the cam shaft. The yoke is so positioned that each bearing 6 and 8 contacts the cam 2 at diametrically opposed points on the cam surface with the springs biasing the bearings toward the cam. Each plunger head 14 is slidably mounted in a stationary guideway 20 by a slide-foot 12.

The cams are designed and ground so that there is a dwell on each end of the stroke with minimum acceleration on stroke reversals. Plunger velocities increase until at cam angle where the plunger velocity is a maximum. By keeping the plunger velocities and accelerations low at the end of each stroke, the valves are allowed to open and close while the flow rates are low. Since the valve lift and flow rate is proportional to the plunger speed, the maximum lift and velocity through the valve is at the middle of the stroke when the plunger velocity is at its maximum. The suction pressure required to overcome suction manifold inertia being proportional to the plunger acceleration, the cam type pump requires less head than a typical crank driven pump where the maximum piston acceleration occurs at the beginning of the stroke with zero acceleration at the middle of the stroke. The suction pressure required to overcome inertia is a much larger portion of the total suction head than that required to lift the suction valves and overcome frictional losses. The pump is motor-driven through the cam shaft.

The plunger exits from the cam enclosure through bearing seal 21 (shown in more detail in FIG. 4) and enters the cylinder 17 through the cylinder plunger seal 16. Fixed to the plunger, between the seals 21 and 16 is a concentric ring 22 which indicates at a glance whether the plungers are reciprocating.

Referring now to FIG. 6 in which are shown details of the cylinder and cylinder sealing cartridge 23, it can be seen that the cartridge 23 includes a cap 24, ribs 25, a packing case 26, and packing 27. The resilient packing 27 is held concentrically around the plunger by the packing case 26. One end of each of the four ribs is held slidable within the packing case by rivets 28. The other end of each of the four ribs is attached to the cap 24. This arrangement allows the cartridge adjusting system 29 to control the sealing ability ofthe packing 27 by putting pressure on the cap 24. This action, in turn, causes the ribs to compress the packing in the packing case. It also allows the whole cartridge to be extracted at once. Furthermore the ribs are narrow and few, thereby representing little resistance to flow in the cylinder. Threaded holes 30 are provided for easy extraction using a puller.

The use and operation of the invention will now be readily understood in view of the above description. Starting with the plunger extended into the cylinder to its maximum extent, the cam is positioned with its lobe directed toward the plunger as shown in FIG. 3. Assuming that the cam shaft 1 in FIG. 3 is driven clockwise by an external motor, the following bearing 8 will be driven rearward, withdrawing the plunger from the cylinder. As already noted, the cam is so designed that plunger acceleration at extremes is minimized and intermediate plunger velocity is maximized. This deviates from the sinusoidal motion of a piston driven by crank and connecting rod or scotch yoke. The present plunger motion combines with time lags to give the resultant output pressure time-valve a sinusoidal form. The resultant input and output fluid streams, when combined with one matching pumping unit 180 out of phase, have a consistance of pressure impossible with such a system driven by conventional means. Furthermore, the characteristics of the present motion cause less shocking acceleration and pressure change on input and output valves, seals, plungers and yoke bearings.

Returning to the discussion of FIG. 3, as the plunger moves rearward with slow but increasing velocity, resulting suction in the cylinder, closes the output valve 19, allows the input valve 18 to open and draws fluid from the input manifold 32 that feeds all of the cylinders. The plunger is drawn to its rearward position and allowed to dwell. During the dwell, the fluid continues to enter, the section in the cylinder is reduced, and the output valve 19 is allowed to open. The cam then starts pushing against the forward bearing 6, pressure in the chamber builds, and input valve 18 closes. The plunger, thereafter, traverses the cylinder and drives the fluid through the output valve 19. The plunger motion is such that the resulting input and output pressure always retain a sinusoidal character. The resultant output of two such cylinders of equal configuration but out of phase will be constant pressure.

Should it be observed, through observation window 33, that seal 16 is leaking, the sealing ability of the sealing material can be adjusted without stopping the pump. Crank 34 is turned, it presses on the cap 24, through the ribs 25 and acts against the packing 27. Should the seals require replacement, the pump is stopped, access port 35 is unscrewed, the cap, and with it the entire cartridge, is extracted, a new cartridge placed and the port closed.

Although the pump shown on the drawings comprises four pumping units divided into two groups, it is to be understood that it may contain any even number of units, either less or more than four.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent 1. A multiple cylinder pump, comprising a. a plurality of hollow cylinders each having geometrically opposied first and second boundaries,

b. a plurality of plungers, each having a first end and a second end, said first end of each plunger being adapted to enter one of the cylinders through an aperture in said first boundary,

c. reciprocating means causing the first end of the plunger to reciprocate within the cylinder,

(1. sealing means provided at each aperture, to control leakage through the aperture, the sealing means including a sealing case concentric to each plunger and open to the first end of the plunger and sealing material within each said case and contacting said plunger,

e. adjusting means positioned on said second boundary adapted to adjust the sealing ability of the sealing means, the adjusting means including spaced ribs extending longitudinally within each cylinder, the ribs extending from the secondary boundary into the sealing case, and operable to compress the sealing material to increase its sealing ability without interrupting pumping operation,

f. an access port on each seond boundary adapted to allow removal of said sealing means, the movement of a first end of the ribs in the case being limited to movement within the case by a radially directed element connecting the case to the ribs and allowing the case to be removed from the pump through the port by pulling on a cap connected to said ribs, and

g. input and output parts suitable for controlling flow through the cylinders.

2. A multiple cylinder pump as recited in claim 1 in which the reciprocating means includes a common cam shaft for all cylinders, and a cam on the cam shaft associated with each plunger.

3. A multiple cylinder pump as recited in claim 2 in which eccentrics are provided on the cam shaft for dynamic balancing of the cam shaft.

4. A multiple cylinder pump as recited in claim 1 in which a pulling cap is provided for each access port, in which pulling cap, ribs, sealing material and sealing case form an easily removable unit, in which the unit sealing material. 

1. A multiple cylinder pump, comprising a. a plurality of hollow cylinders each having geometrically opposed first and second boundaries, b. a plurality of plungers, each having a first end and a second end, said first end of each plunger being adapted to enter one of the cylinders through an aperture in said first boundary, c. reciprocating means causing the first end of the plunger to reciprocate within the cylinder, d. sealing means provided at each aperture, to control leakage through the aperture, the sealing means including a sealing case concentric to each plunger and open to the first end of the plunger and sealing material within each said case and contacting said plunger, e. adjusting means positioned on said second boundary adapted to adjust the sealing ability of the sealing means, the adjusting means including spaced ribs extending longitudinally within each cylinder, the ribs extending from the second boundary into the sealing case, and operable to compress the sealing material to increase its sealing ability without interrupting pumping operation, f. an access port on each second boundary adapted to allow removal of said sealing means, the movement of a first end of the ribs in the case being limited to movement within the case by a radially directed element connecting the case to the ribs and allowing the case to be removed from the pump through the port by pulling on a cap connected to said ribs, and g. input and output parts suitable for controlling flow through the cylinders.
 2. A multiple cylinder pump as recited in claim 1 in which the reciprocating means includes a common cam shaft for all cylinders, and a cam on the cam shaft associated with each plunger.
 3. A multiple cylinder pump as recited in claim 2 in which eccentrics are provided on the cam shaft for dynamic balancing of the cam shaft.
 4. A multiple cylinder pump as recited in claim 1 in which a pulling cap is provided for each access port, in which pulling cap, ribs, sealing material and sealing case form an easily removable unit, in which the unit is so adapted that removal of the pulling cap from the pump causes removal of the whole unit and in which the cap can be acted upon to adjust the sealing ability of the sealing material.
 5. A multiple cylinder pump as recited in claim 4 in which each access port is provided with a hatch, and each hatch is provided with an adjusting element which can act on the cap to adjust the sealing ability of the sealing material. 